touch off vs trigger

touch off is not a noun while trigger is a noun.

Word	Noun	Adjective	Verb	Adverb
touch off	No	No	Yes	No
trigger	Yes	No	Yes	No

As verbs, touch off and trigger are synonyms defined as:

Other synonyms of touch off include activate, actuate, set off, spark, spark off, trigger off, trip.

touch off (noun)	trigger (noun)
	an act that sets in motion some course of events
	lever that activates the firing mechanism of a gun
	a device that activates or releases or causes something to happen

touch off (verb)	trigger (verb)
put in motion or move to act	release or pull the trigger on
	put in motion or move to act